An easy way to get some extra cash is at the begginnig of the game when you fight all the villagers and the Exicutioner, kill the Exicutioner then pick up the Gold Ring he drops and pick up the Scorpion (VZ61) and what ever cash dead Majini drop and before the cut scene quit the game and sell all the VZ61 and the ring and then when you continue the game it will start off right before the fight you just had and you can keep killing the Exicutioner and picking up the ring he drops and the VZ61 and just keep selling them. The Gold Ring itself is worth $5,000 and the gun $200.
And if you don't want to keep doing that you can go to 3-1, there's $2,000 worth of stuff right there (a ruby and a brown beetle) and after you grab those leave the game and then load it up again and you can keep doing that for easy money.